Sorbet is a frozen dessert made from fruit or juice. Sherbet is also made from fruit and is a frozen dessert; however, sherbet typically includes dairy. Sorbet does not. Both words do come from the same word base tracing back to the Arabic sharba or drink.
Sorbet can be pronounced (sor bay) or (sor bet). The plural is made by adding an s. The pronunciation then changes to (sor bays) or (sor bets).